The present invention relates to a pulverizer bowl mill and, more specifically, to an arrangement for supporting a vane wheel assembly of a pulverizer bowl mill.
It has long been known in the prior art to provide apparatus that is suitable for employment for purposes of effecting the grinding, i.e., pulverization, of materials, with coal being one such material. More specifically, the prior art is replete with examples of various types of apparatus that had been used heretofore to effect therewith the grinding of a multiplicity of different kinds of materials. In this regard, in many instances discernible differences of a structural nature can be found to exist between individual ones of the aforesaid apparatus. The existence of such differences is in turn attributable for the most part to the diverse functional requirements that are associated with the individual applications in which such apparatus are designed to be employed. For instance, in the selection of the particular type of apparatus that is to be utilized for a specific application one of the principal factors to which consideration must be given is that of the nature of the material that is to be ground in the apparatus.
One particular type of coal pulverizing apparatus, which is to be found in the prior art is an apparatus, most commonly referred to in the industry by the name bowl mill. The latter apparatus obtains its name by virtue of the fact that the pulverization, i.e., grinding, of the coal which takes place therein is effected on a grinding surface that in configuration bears a resemblance to a bowl. Reference may be had by way of exemplification to U.S. Pat. No. 3,465,971, which issued Sep. 9, 1969 to J. F. Dalenberg et al., and/or U.S. Pat. No. 4,002,299, which issued Jan. 11, 1977 to C. J. Skalka, both of the latter patents having been assigned to the same assignee as the instant application, for a teaching of the nature of the construction and the mode of operation of a prior art form of bowl mill that is suitable for use in a coal fired power generation system to effectuate the pulverization of the coal that is to be burned as fuel therein.
Continuing, in a coal pulverizing apparatus of the type to which reference has been had hereinbefore, a primary classification is had within the bowl mill of the material, e.g., coal, that is being pulverized therewithin. As employed herein the term primary classification is intended to refer to the separation of pulverized material from the air in which such material is entrained. In particular, reference is had here to that separation of pulverized material, which occurs as a consequence of causing the air within which the pulverized material is entrained to follow a tortuous path through the bowl mill whereby in the course of changing directions of flow the larger of the particles of the pulverized material lose their momentum and are made to return to the surface of the grinding table whereat they are subjected to further pulverization.
In accordance with the teachings of the prior art, it has been known to employ a vane wheel assembly in a bowl mill for purposes of accomplishing the aforedescribed primary classification of pulverized material therewithin. By way of exemplification, such a bowl mill comprises the subject matter of U.S. Pat. No. 4,523,721, which issued on Jun. 18, 1985 to T. V. Maliszewski et al. and which is assigned to the same assignee as the present invention.
Efforts to rigidly secure a vane wheel assembly to the grinding table of a bowl mill for rotation therewith had led to problems such as cracking due to differential thermal expansion. Accordingly, there remains a need in the prior art for an arrangement that reliably and accurately secures a vane wheel assembly to a rotating grinding table of a bowl mill yet which improves over the prior art.
It is an object of the present invention to provide an arrangement for securing a vane wheel assembly to the rotating grinding table of a bowl mill in a reliable manner.